JPA 菜鸟教程 14 自定义类型-@Embedded+@Embeddable

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自定义类型

在hibernate中实现自定义类型，需要去实现UserType接口即可或者以Component的形式提供。

JPA的@Embedded注解有点类似,通过此注解可以在Entity模型中使用一般的java对象,不过此对象还需要用@Embeddable注解标注。

需求产生

Employee类有一个address属性，
address应该有city,street两个属性,
一般的写法直接在Employee类中写两个属性:
private String city;
private String street;

现在可以用一个Address类来代替此类写法，Address类包含了city和street,如此一来,我们在Employee类只要这样写:
private Address address;

ddl语句

CREATE TABLE `t_employee` (  `id` bigint(20) NOT NULL AUTO_INCREMENT,  `city` varchar(255) DEFAULT NULL,  `street` varchar(255) DEFAULT NULL,  `name` varchar(255) DEFAULT NULL,  PRIMARY KEY (`id`)) ENGINE=InnoDB AUTO_INCREMENT=2 DEFAULT CHARSET=utf8;

Address

package com.jege.jpa.embeddable;import javax.persistence.Embeddable;/** * @author JE哥 * @email [e-mail] * @description:实现自定义类型，在hibernate里面需要实现UserType接口 */@Embeddablepublic class Address {  private String city;  private String street;  public String getCity() {    return city;  }  public void setCity(String city) {    this.city = city;  }  public String getStreet() {    return street;  }  public void setStreet(String street) {    this.street = street;  }}

Employee

package com.jege.jpa.embeddable;import javax.persistence.Embedded;import javax.persistence.Entity;import javax.persistence.GeneratedValue;import javax.persistence.Id;import javax.persistence.Table;/** * @author JE哥 * @email [e-mail] * @description:@Embedded注解 */@Entity@Table(name = "t_employee")public class Employee {  @Id  @GeneratedValue  private Long id;  private String name;  @Embedded  private Address address;  public Long getId() {    return id;  }  public void setId(Long id) {    this.id = id;  }  public String getName() {    return name;  }  public void setName(String name) {    this.name = name;  }  public Address getAddress() {    return address;  }  public void setAddress(Address address) {    this.address = address;  }}

MainTest

package com.jege.jpa.embeddable;import javax.persistence.EntityManager;import javax.persistence.EntityManagerFactory;import javax.persistence.Persistence;import org.junit.After;import org.junit.AfterClass;import org.junit.Before;import org.junit.BeforeClass;import org.junit.Test;/** * @author JE哥 * @email [e-mail] * @description:自定义类型-@Embedded+@Embeddable测试 */public class MainTest {  private static EntityManagerFactory entityManagerFactory = null;  private EntityManager entityManager = null;  @BeforeClass  public static void setUpBeforeClass() throws Exception {    entityManagerFactory = Persistence.createEntityManagerFactory("com.jege.jpa");  }  @Before  public void setUp() throws Exception {    entityManager = entityManagerFactory.createEntityManager();  }  @Test  public void persist() {    Address address = new Address();    address.setCity("beijing");    address.setStreet("王府井大街");    Employee employee = new Employee();    employee.setAddress(address);    employee.setName("jege");    entityManager.getTransaction().begin();    entityManager.persist(employee);    entityManager.getTransaction().commit();  }  @After  public void tearDown() throws Exception {    if (entityManager != null && entityManager.isOpen())      entityManager.close();  }  @AfterClass  public static void tearDownAfterClass() throws Exception {    if (entityManagerFactory != null && entityManagerFactory.isOpen())      entityManagerFactory.close();  }}

源码地址

https://github.com/je-ge/jpa

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